Into Unscientific

“.”

In the conference room.

Looking at the title of the paper in front of him, Academician Xue Qikun subconsciously made a somewhat funny move:

He slowly took off his glasses, rubbed his eyes vigorously with his knuckles twice, and then he looked at the paper with wide eyes again.

Then

Well, the line of words still did not change:

"Exploration of the mechanism of high-temperature superconductivity phenomenon".

Seeing this situation.

Bang bang bang——

Academician Xue Qikun's big heart, which did not fluctuate much when he won the Buckley Prize, suddenly beat violently.

In this era, the concept of superconductivity is not unfamiliar to many people.

In physics, superconductivity is a phenomenon in which the resistance of a material becomes 0 when it is below a certain temperature. The transformed material is called a superconductor.

Students who have been to high school should know it.

In a circuit, the charges in the wire will move like a runner under the drive of voltage, thus forming a current, but the resistance of the conductor will hinder their movement.

If the circuit is composed of superconductors, the charges can run freely in the circuit and the current will continue to flow.

In a loop made of superconducting lead, no signs of weakening of the current can be observed for several months.

The superconductivity phenomenon was first discovered by Onnes in 1911. He used liquid helium to cool mercury and found that the resistance of mercury became zero at -268.98°C, thus opening the door to the superconducting world.

From a business and technological perspective.

Once superconducting materials can be applied, human technology will usher in a new round of leaps and bounds.

For example, in the field of power transmission, household appliances, and transportation - at that time, the wheels of all moving objects can be removed.

At that time, the Formula One Championship will be replaced by the low-altitude hovering car race in "Star Wars", and you can drive a hover car and a hover boat to every corner of the world.

But unfortunately, the ideal is full and the reality is very skinny.

So far, the practical application of superconductors is still mainly concentrated in specific situations such as particle accelerators, magnetic levitation, and superconducting quantum interferometers.

In power engineering, especially the highly anticipated long-distance transmission of superconducting wires, large-scale application is still a long way off.

What limits the wide application of superconductors?

There is only one fundamental reason:

Temperature.

The temperature at which a material turns into a superconductor is called the superconducting critical temperature (Tc). Only below this Tc can a superconductor maintain its superconducting properties.

However, the Tc of most materials is very low, basically below -220°C, and requires the help of liquid nitrogen or liquid helium to maintain a low temperature environment.

Imagine.

You have worked hard to build a superconducting transmission line of hundreds of kilometers, and you still need to immerse it in liquid nitrogen for cooling. How expensive it is.

So in order to make superconductors more widely used, it is necessary to find materials with higher Tc, preferably at room temperature (about 25°C) that can maintain superconducting properties.

Since the discovery of superconductivity, physicists have never stopped looking for high-Tc superconductors, but it has always been difficult.

In the first 70 years after the discovery of superconductivity, it was difficult to even break through the upper limit of Tc of -240°C.

Fortunately, physicists later discovered superconductors with Tc exceeding -173℃. The current record holder for the highest critical temperature of superconductors is hydrogen sulfide under 1.5 million atmospheres of pressure, with Tc of about -73℃, which is still a certain distance from the ideal room temperature. Such high pressure conditions also mean that it is difficult to apply in practice.

At the same time.

Based on the above concepts, superconducting materials have derived two small branches:

Room temperature superconductivity and high temperature superconductivity.

In general.

We call superconductors with a critical temperature higher than 40K high temperature superconductors, and superconductors with a critical temperature higher than about 300K room temperature superconductors.

That is to say, in the superconducting world, "room temperature" is actually much higher than "high temperature".

What's more special is that.

Until this period, the physics community still has no conclusion on the complete mechanism of high temperature superconductivity.

This is a black hole in the field of condensed matter physics. Today, there are only two problems that are generally recognized as unresolved in condensed matter physics:

One is the strongly correlated system, and the other is the complete mechanism of high temperature superconductivity. (Note: Some people also regard the two as one problem, just like whether cherries and early cherry are the same species, it depends on how you look at it)

In addition, even the fractional quantum Hall effect that Academician Xue Qikun specializes in can only be regarded as a classical problem, not a dead end.

Indeed.

Because this mechanism is infinitely close to the theoretical level, it is actually not very likely to win the Nobel Prize by relying on it alone, but for practitioners in the physics community, the significance of unlocking this mechanism is no less than winning the Nobel Prize.

Nowadays, there are many teams engaged in mechanism deduction at home and abroad. Even Academician Xue Qikun has two research groups promoting this topic. The leaders of the project groups are one Changjiang and the other Jieqing.

The result is unexpected.

Academician Xue Qikun actually saw such a shocking title at Xu Yun's master's defense?

Is Xu Yun deliberately skirting the edge and finally playing an ambiguous word game?

Or did he really pick this pearl of condensed matter physics?

"Mr. Zhou, Mr. Zhou!"

Just when Academician Xue Qikun was inexplicably shocked, a burst of urgent sound suddenly came from a communication device on the desktop where Academician Zhou Guangzhao was sitting:

"Mr. Zhou, your heartbeat has just exceeded 100! Mr. Yang and Mr. Wang's data are also very high!"

"Did something happen? Do we need a health care team to come in?"

Mentioned earlier.

At this time, three of the seven people in the room (including Xu Yun) were close to or over 100 years old. The youngest of the three, Zhou Guangzhao, was 95 years old.

Therefore, in order to ensure the safety of several national treasures, the Academy of Sciences prepared a medical team in advance to conduct real-time monitoring off-site through equipment worn by several big shots.

Just now, the doctor in charge of health care suddenly discovered an anomaly:

The heart rates of several big guys began to rise at the same time. Among them, Academician Zhou Guangzhao's value even jumped from 57 to a peak of 102 per minute, which scared the doctors in the health care team and their heart rates also soared to 180+.

"I'm fine."

Just as the leader of the medical team was wondering whether to pick up the medical kit and rush into the room, Zhou Guangzhao spoke to the communication device:

"I just saw some unexpected content, so there's no need to come in."

"Mr. Yang and Xi Ji are both fine. We are both conscious. If we really feel unwell, I will inform you."

The person on the other side of the communication device was silent for a while, and finally sighed helplessly:

".receive."

As experts who specialize in providing medical care to these seniors in the scientific research community, the members of the medical team naturally know the tempers of these little old men.

Even though they are usually happy and cheerful, when they encounter academic matters, they become extremely stubborn and cannot be persuaded no matter how hard they try.

On the contrary, those veteran cadres who have retired from the political circle will be more cooperative with the medical team. This is probably the difference between the top liberal arts students and the science students.

After hanging up the communication device.

Academician Zhou Guangzhao leaned back slightly, held Xu Yun's paper in front of him with both hands and looked at it a few more times, then raised his head and looked at Xu Yun:

"Classmate Xu Yun, are you serious about this title?"

Looking at Zhou Guangzhao's slightly scrutinizing gaze, Xu Yun suddenly felt a somewhat complicated emotion in his heart.

In the dungeon, Xu Yun and Zhou Guangzhao could not be said to be friends who exchanged lives for their lives. At least they could be said to be revolutionary comrades who lived together day and night. They worked together to complete many arduous tasks. However, in reality, Mr. Zhou had never met him before. Bai Dian said in a slightly questioning tone.

Comrades in the copy, strangers in reality.

The so-called misplaced time and space is probably what it feels like.

However, this emotion was only fleeting in Xu Yun's heart, and he soon adjusted himself:

"Hello, Academician Zhou, I am honored that you can participate in my graduation defense. I can generally understand some of your thoughts - after all, this topic may involve a relatively high level and is not something that a master's degree can touch. "

"But on the other hand, from my personal point of view, this master's defense is also an important life node that cannot be missed. I have no reason to ruin this defense."

"So to put it bluntly, I am quite confident in the quality of the content of this paper."

When Xu Yun spoke, his posture was very low, but his expression was not too restrained. He answered Zhou Guangzhao's questions in a tactful but firm manner.

After all, it's exactly what he said.

The paper he wrote is not just a headline, nor is it ambiguous, but it clearly explains the complete mechanism of high-temperature superconductivity.

"."

Zhou Guangzhao was silent for a while after hearing this, turned to look at Xue Qikun, and said to Xu Yun:

"In that case, classmate Xu Yun, you can start your defense."

Seeing this, Xu Yun nodded, walked from the side of the podium to the center of the podium, quickly scanned the scene, and said:

"Hello, fellow reviewers, I am today's respondent Xu Yun. I am 24 years old and a graduate student. My student number is 114514."

"The content of my defense today is "Discussion on the Mechanism of High-Temperature Superconductivity", a very hot and controversial topic in the field of condensed matter."

Xu Yun paused as he spoke, then pressed the remote control pen, and the image of Xu Yun's paper was quickly projected on the projector:

"High-temperature superconductors generally refer to superconductors with a superconducting critical temperature above 40K, which is a concept relative to low-temperature superconductors such as mercury and lead, which have a critical temperature of about 10K."

"As for applications, it usually refers to cuprate ceramic superconductors such as YBaCuO and HgBaCaCuO. Their superconducting critical temperature is around 100 K, which is higher than the concept."

"The phenomenon of superconductivity was first discovered by Onness in 1911. Then 44 years after the discovery of superconductivity, three scientists, Cooper and Schrieffer, proposed the famous BCS theory, which satisfactorily explained the behavior of superconductors such as Hg and Pb. Superconductivity - for which they won the Nobel Prize in Physics in 1972."

"BCS theory can well explain some properties of low-temperature superconductors, such as energy gaps, Meissner effects, and isotope effects. However, many phenomena that violate BCS theory have been found in high-temperature superconductors, such as pseudo-gaps, linear resistance, and electric charges. Spin separation, strong superconducting phase fluctuations, etc.”

"This suggests the existence of strongly correlated electronic systems in high-temperature superconductors that are difficult to deal with using perturbation theory or mean fields."

"Therefore, I abandoned the framework of BCS theory in my paper and adopted another idea to explain high-temperature superconductivity."

Note:

Tomorrow will be the finale, and it will be a big chapter. My hands are shaking a little when I write this sentence. The book will be published on November 26, 2021, a full two and a half years. Thank you for your company along the way.